Enzymatic Synthesis of Alternatingly 6-O-Carboxymethylated Chitotetraose by Selective Glycosidation with Chitinase Catalysis

An alternatingly 6-O-carboxymethylated chitotetraose derivative was selectively synthesized via enzymatic glycosidation of a 6ʹ-O-carboxymethylated chitobiose oxazoline derivative catalyzed by chitinase. The enzyme from Streptomyces griseus acted as an efficient catalyst for the reaction, giving rise to N,Nʹ,N",N"ʹ-tetraacetyl-6ʹ,6"ʹ-di-O-carboxymethylchitotetraose in a 42% yield.